The water gas shift reaction has been employed in industrial processes to produce H2 from water vapor and carbon monoxide. The basic water gas shift reaction is set forth in Equation 1, provided below.CO+H2O ⇄CO2+H2  Eq. 1)Use of a water gas shift catalyst in the exhaust stream of a richly operated dedicated cylinder in a dedicated exhaust gas recirculation engine (operating at an air to fuel ratio of 13.5:1 or less) would be desirable to increase H2 levels in the exhaust gas. Increased H2 levels lead to further improved burn durations, combustion stability, decreased HC emissions, and greater knock resistance which can directly translate into enhanced engine efficiency.
However, when employed in an engine, and in particularly in conjunction with a richly operated dedicated cylinder, the exhaust gas composition is substantially different than the exhaust gas of industrial processes. It has been observed that when water gas shift catalysts are used for only few hours in the exhaust gas environment, and particularly in conjunction with a richly operated dedicated cylinder, a loss in water gas shift reactivity occurs. The loss in water gas shift reactivity being indirectly measured by the carbon monoxide conversion efficiency of the water gas shift catalysts.